`lbl_seq()`

labels intervals sequentially, using numbers or letters.

## Details

`start`

shows the first element of the sequence. It must contain exactly *one*
character out of the set "a", "A", "i", "I" or "1". For later elements:

"a" will be replaced by "a", "b", "c", ...

"A" will be replaced by "A", "B", "C", ...

"i" will be replaced by lower-case Roman numerals "i", "ii", "iii", ...

"I" will be replaced by upper-case Roman numerals "I", "II", "III", ...

"1" will be replaced by numbers "1", "2", "3", ...

Other characters will be retained as-is.

## See also

Other labelling functions:
`lbl_dash()`

,
`lbl_discrete()`

,
`lbl_endpoints()`

,
`lbl_glue()`

,
`lbl_intervals()`

,
`lbl_manual()`

,
`lbl_midpoints()`

## Examples

```
chop(1:10, c(2, 5, 8), lbl_seq())
#> [1] a b b b c c c d d d
#> Levels: a b c d
chop(1:10, c(2, 5, 8), lbl_seq("i."))
#> [1] i. ii. ii. ii. iii. iii. iii. iv. iv. iv.
#> Levels: i. ii. iii. iv.
chop(1:10, c(2, 5, 8), lbl_seq("(A)"))
#> [1] (A) (B) (B) (B) (C) (C) (C) (D) (D) (D)
#> Levels: (A) (B) (C) (D)
```